In this investigation was obtained a maximum of 7.62 g/L of citric acid fermenting the whey hydrolyzed at 30 ºC and an initial pH of 6.5. The optimization determined an initial pH of 7, a temperature of 31ºC and a whey hydrolyzed to reach 7.92 g/L of acid. However, only 4.1 g/L was reached due to the scale-up.